1. Field of the Invention
The present invention relates to the field of injectors, and more particularly to a novel fluid injector device for combining and mixing at least two separate and different fluids within an enclosed chamber preparatory to and during combustion and for use with burners including underoxidized burners, in connection with fuel cells, internal combustion engines and the like.
2. Brief Description of the Prior Art
In the past, concentric streams of gaseous fuel and oxidizer in fluid form impinged onto a plate perpendicular to the flow of the streams which induces initial mixing. The design of the plate is such that the stream is directed rearward into the burner under conditions where further mixing occurs, as well as induction of the surrounding combustion products to provide internal circulation. The initial feed mixing produced in this manner is generally so rapid that chemical reaction between the fuel and oxidizer does not occur until the stream is no longer within a restricted enclosure so harmful results are avoided. Also, since combustion does not occur until mixing is complete, pockets with diverse air/fuel ratios cannot occur which, if near stoichiometric could lead to high temperatures with destructive effects or undesirable products. Previous injectors, as disclosed in U.S. Pat. Nos. 5,437,123 and 5,546,701 have been successfully used with air and methane feeds each at 1000.degree. Fahrenheit, with vaporized liquid fuel feeds and air at 1000.degree. Fahrenheit and with mixtures of CO, H.sub.2, N.sub.2 and air also at high temperatures, etc.
However, when the fluid feeds were methane as a fuel with augmented air consisting of a 50--50 mixture of oxygen and nitrogen, all preheated to 1000.degree. Fahrenheit, unacceptable destruction occurred in the vicinity of the injector. Apparently, the extreme reactivity of these feed components at this condition resulted in ignition before the reactants completely mixed, so areas of near stoichiometric ratios occurred with temperatures high enough to cause destruction. Also, the injector tip was not protected against high temperature of the combustion.
Therefore, a long-standing need has existed to provide an improved injector which will minimize the above noted problems employing a modification in which one of the feeds induces the other feed external to the injector. This is broadly achieved by adjusting the diameters of the concentric tubes so that the velocity of feed in the one tube is about 1.25 times or twice that of the feed in the other tube. Such a treatment reduces or eliminates the need for a plate perpendicular to the flow in order to induce initial mixing. Also, protection of the injector tip from after surrounding gas high temperatures must be considered.